Laser applicator set

ABSTRACT

The invention discloses a laser application set, which is an interventional application set for minimum invasive, laser-induced thermotherapy of soft-tissue tumors.  
     In accordance with the invention the laser application set is designed in such a manner that an introductor tube ( 6 ) with a stylet ( 12 ) is provided and accommodates a tunneled catheter ( 17 ) with an internal stylet ( 20 ).

[0001] The present invention discloses a laser application set, which isan interventional application set for minimum invasive laser-inducedthermotherapy of soft-tissue tumors.

[0002] It is known as state of the art that laser radiation whichemerges from an optical waveguide, e.g. the irradiation of an Nd:YAGlaser at 1064 nm, employing a silica glass optical fiber (of the PCS,HCS or ALL SILICA type) as beam guidance system, may be used to causeradial-symmetric coagulation necroses in biological tissue. In order todo so, the light-conducting fiber is either placed upon the tissue orinserted into the tissue. However, the disadvantage of this method oftherapy is that there occurs a high power density at the place ofcontact between fiber end area and tissue which, already above some 100mW luminous power and depending on the fiber diameter, results in acarbonization of the tissue surface and thus, due to the high level ofcarbon absorption, prevents the further diffusion of radiation withinthe tissue.

[0003] Further an application device for laser radiation (DE4137983A1)is known, in which the beam-conducting end of the optical waveguide thatfaces the object to be treated is arranged in a tubular enveloping bodywhose front face is transparently shut to laser radiation, in particularin a plastic hose whose front end facing said object is air- andfluid-tight sealed, with the front face of the enveloping body and/orthe end of the optical waveguide being equipped with a spreading devicefor laser radiation that has a spreading volume. There, also multiplechambered hoses are employed in order to provide possibly requiredcooling via a connected distributor piece.

[0004] Also known is a U.S. Pat. No. 5,312,392 “A method of treatingbenign tumors”. In which a trocar, that contains an optical waveguide,is inserted into the tumor to be treated. The position of the trocarwith the optical waveguide is monitored using ultrasound. Thedisadvantage of this method is that any repositioning of the trocar withthe optical waveguide is only possible with a new puncture.

[0005] The disadvantage of all previously applied methods of therapy isthat they fail to allow for a repositioning of the relevant envelopingbody which contains the laser and, hence, any faulty positioning of thelaser or the enveloping body, respectively, requires a new puncture. Afurther disadvantage is that with a defective laser wire (opticalwaveguide) yet another intervention into the soft-tissue tumor to betreated becomes necessary.

[0006] The object of the invention is the implementation of a laserapplication set which ensures a gentle treatment of a patient andfacilitates monitoring by means of a computer tomograph or a magneticresonance tomograph, respectively.

[0007] The aim of the invention is the creation of a laser applicationset which neutralizes the disadvantages of the prior art and theprevious methods of therapy by providing an interventional applicationset for laser therapy which enables a repositioning and requires only asingle puncture of the tumor to be treated.

[0008] The aim according to the invention is attained by implementing alaser application set in accordance with Nos. 1 to 9 of the patentclaims.

[0009] The laser application set consists of an introducer tube with aninternal stylet. The internal stylet is locked with the introducer tubeby means of a thread. The internal stylet is designed in such a mannerthat it projects by approx. 1 cm over and beyond the end of theintroducer tube and has a pointed form. The stylet is of a hollowconstruction. A grip end at the external end of the stylet may be usedto undo its locking by turning, after which the stylet may be removedfrom the introducer tube. The proximal end of the introducer tube isprovided with a T piece. A silicone lamella is placed between the Tpiece and the introducer tube proper in order to provide a highelasticity during the insertion into the respective tumor. The siliconelamella is designed as a silicone membrane in the form of aforward-folding buckling lamella. A hose lead with a downstreamthree-way faucet is connected to the T piece. The hose lead and theconnected three-way faucet may be used to apply cooling agents,lubricants and/or other additional local anesthetics. This opportunityof supply essentially contributes to providing a largely painlesstherapy also for capsular lesions. In addition, the hose lead allows forblood control of the patient under treatment during the therapy session.An external thread to lock the stylet is located opposite the siliconelamella of the T piece. Moreover, the T piece is equipped with amembrane which prevents any fluids from leaking during the therapysession.

[0010] A further preferred embodiment is the provision of the introducertube with marks which facilitate the exact positioning of theapplication set. The individual marks are appended at a distance of 1 cmfrom each other.

[0011] A further component of the laser application set is a tunneledcatheter with an internal stylet. The tunneled catheter with theinternal stylet is inserted upon the removal of the stylet from theintroducer tube. The tunneled catheter is designed in such a manner thatits distal end is air- and fluid-tight sealed and has a tunneledcatheter tip which significantly contributes to the possibility that arepositioning may be made of the tunneled catheter in the tumor to betreated. The tunneled catheter is also provided with marks at a distanceof 1 cm from each other which allow for an exact positioning of thetunneled catheter when inserted into the introducer tube. The beginningof the marking on the tunneled catheter is designed in such a mannerthat, upon reaching the first mark, the catheter projects approx. 30 mmfrom out of the introducer tube, which is important for the operabilityof the laser application set. Within the tunneled catheter there is aninternal stylet whose end is equipped with a grip end for its removal.The internal stylet is made from stainless steel, which preferentiallyconsists of a paramagnetic material. This stainless steel wire iswrapped with a synthetic sheathing. The essential fact is that theinternal stylet provides stabilization to the insertion of the tunneledcatheter into the introducer tube and, hence, enables the exactpositioning of the tunneled catheter tip into the tumor to be treated. Afurther essential feature of the invention is that the introducer tubewith the stylet as well as the tunneled catheter with its internalstylet are made from materials which may be used for the monitoring ofthe method of therapy by means of computer tomography (CT) or magneticresonance tomography (MRT), respectively. The materials of theintroducer tube and the stylet as well as the tunneled catheter arepreferably from synthetic materials, with PE, PTFE, FEP plastics beingemployed.

[0012] The laser application set according to the intervention has thefollowing advantages over the known application sets for laser therapiesof soft-tissue tumors.

[0013] The marks appended to the introducer tube allow for an exactpositioning of the introducer tube on the patient. The exact positionrelation of the laser application set to the lesion is of decisivesignificance for a successful therapy. Further, it can be establishedthat the membrane located in the T piece of the introducer tubefacilitates a safe and non-slipping positioning of the tunneled catheteraccording to the invention. The tunneled catheter is thermoresistant upto a max. 400° C. and its distal end is air- and fluid-tight sealed. Thetunneled catheter, which thus prevents a direct contact between thelaser applicator and the patient, is equipped with an internal stylet,consisting of a wire from paramagnetic material, that essentiallycontributes to the stabilization of the tunneled catheter during itsinsertion. Thus, on the one hand the tunneled catheter may be kept thinwhile, on the other, the required stabilization is still achieved. Themarks appended to the introducer tube allow for an exact positioning ofthe introducer tube and prevent a fusion of the introducer tube when thelight transmitting tunneled catheter fails to project sufficiently fromthe introducer tube system that is impervious to laser light. Arepositioning of the tunneled catheter, which is inserted internallyinto the introducer tube, is permitted as a result of permanentmonitoring by computer tomograph or a magnetic resonance tomograph,respectively. In case that a defect or other malfunction is found duringthe insertion of the laser applicator a new laser applicator may beinserted at any time without having to commence a new therapy phase. Theappropriate composition of materials has created a laser application setwhich is compatible with monitoring by CT, MRT or nuclear magneticresonance tomography (NMRT), respectively.

[0014] A further advantage according to the invention lies in that uponthe completion of the laser therapy and removal of the introducer tubetherapeutic agents, such as tissue glue, may be introduced via the hoselead and the pertaining three-way faucet, and thus a dispersion of thecells of the treated tumor is inhibited which previously had been aserious disadvantage in the laser therapy of tumors.

[0015] Furthermore, the laser application set according to the inventionfacilitates the single-time puncture of the tumor to be treated, thuspreventing any dispersion of the tumor.

[0016] The following aspects should be considered as further applicationindications of the laser application set according to the invention. Thelaser application set according to the invention enables a percutaneouslaser therapy of, e.g., hepatic metastases which cannot be surgicallyremoved due to their distribution. Also operable metastases may besubjected to laser therapy when a patient refuses surgery. In addition,a patient may be brought into an operable condition by employing thelaser application set to treat one or more metastases by lasertreatment. The set allows for the treatment of metastases of a max.diameter of 4 cm. Further fields of application of the laser applicationset worth mentioning are the palliative therapy of benign tumors in thehead/neck region and the percutaneous therapy of soft-tissue tumors inthe pelvic region.

[0017] The tunneled catheter is designed with a connection piece. Thelocking piece of an inner tunneled catheter is appended to theconnection piece, with the inner tunneled catheter being located withinthe tunneled catheter of the laser application set. A flushing and/orcooling agent outlet is provided at the distal end of the inner tunneledcatheter The connection piece of the tunneled catheter and the lockingpiece of the inner tunneled catheter may be firmly interlocked by meansof a sealing thread at the connection piece. The connection piece andthe locking piece are each equipped with connectors to which T piecesare attached. The T pieces may be used to connect a pump for therecirculation of the flushing and/or cooling agent. Thus, a flushingand/or cooling fluid, preferably sterile isotonic sodium chloridesolution, is led via a T piece of the inner tunneled catheter and on viathe connector of the locking piece into the inner tunneled catheter,with the backflow occurring between the inner tunneled catheter andtunneled catheter via the connection piece and the connector to the Tpiece. Thus optimum cooling is provided to the entire area of thepunctured external tissue.

[0018] The locking piece of the inner tunneled catheter is equipped witha membrane sealing. The internal stylet of the laser application set isinserted and removed, respectively, and also the laser applicator isinserted during a therapy session through this membrane sealing. Afurther membrane sealing at the connection piece serves as a sealingwhen the inner tunneled catheter is inserted into the tunneled catheter.

[0019] The particular design of the tunneled catheter provides furtheressential advantages for the use of the laser application set. Theemployment of the laser application set ensures optimum conditions toachieve coagulation necroses with a max. diameter of 20 mm to 25 mm. Itis due to the heat dissipation, that is essentially conditioned by bloodflow in the vessels and diffusion in the tissue, that it is usuallyimpossible in vivo to induce coagulation necroses larger than 2*2*2 cmby using the laser application set without inserting the inner tunneledcatheter. However, the majority of soft-tissue tumors have a size of 3cm to 4 cm when a diagnosis is made. In order to coagulate a volume of4*4*4 cm, with the previous use of the laser application set of the mainpatent, eight laser applications and, hence, eight punctures arenecessary. The laser power is approx. 5 watts applied over a 20-minutetherapy session. What is essential is that the tunneled catheterconfiguration allows the laser application set to achieve coagulationnecroses larger of up to a max. 4.2*4.2*4.2 cm with one laserapplication, during which laser power of up to 30 watts is applied up to15 minutes. The tunneled catheter, which is used as part of the laserapplication set, achieves that high laser powers can only be appliedwhen a cooling of the tissue immediately adjacent to the tunneledcatheter is ensured and thus any carbonization or vaporization of tissueis prevented. Carbonization or vaporization of the tissue immediatelyadjacent to the tunneled catheter prevents a further propagation of thecoagulation zone since the entire laser power at the employed wavelengthof 1064 nm would be absorbed in the immediate vicinity of the tunneledcatheter. In particular the laser application catheter in conjunctionwith the tunneled catheter of the laser application set in the mainapplication yields the below advantages for the patient:

[0020] 1. In order to coagulate a lesion measured to be 4*4*4 cm the useof a tunneled catheter in conjunction with the laser application setrequires only one laser application in the place of eight laserapplications with the laser application set.

[0021] 2. Furthermore, the clear decrease of the number of puncturesreduces the risk of puncture complications, such as hemorrhage, vascularand nerve injuries as well as organ injuries.

[0022] 3. Since the number of punctures required for tumor treatmentdecreases also the risk of tumor dispersion and thus the risk ofvaccination metastasis is reduced.

[0023] 4. Furthermore, the use of the special tunneled catheter inconjunction with the laser application set results in a clear costsaving potential of this method because with a lesion measured to be4*4*4 cm no longer eight puncture tracks have to be sealed wit fibringlue but only one puncture track.

[0024] 5. Normally, a patient does not tolerate eight punctures in onetherapy session, hence, the second half of the tumor often had to besubject to laser therapy in a second therapy session. This secondtherapy session may fall away when the tunneled catheter of the laserapplication set is used.

[0025] 6. In case of lesions up to a diameter of 4 cm the use of thetunneled catheter with the laser application set attains a clearlyhigher probability of a 100% tumor coagulation. Thus, this applicationis able to achieve a clear reduction of the local recurrence rate.

[0026] The advantageous further developments of the invention are,respectively, characterized in the dependent claims or are representedbelow in greater detail together with a description of the preferredpractical example of the invention by means of figures. The figuresillustrate the following:

[0027]FIG. 1 Puncture needle

[0028]FIG. 2 Stainless steel wire;

[0029]FIG. 3 Stylet introducer tube;

[0030]FIG. 4 Introducer tube with T piece;

[0031]FIG. 5 Tunneled catheter;

[0032]FIG. 6 Internal stylet-tunneled catheter;

[0033]FIG. 7 Tunneled catheter with cooler;

[0034]FIG. 8 Tip of the tunneled catheter with cooler.

[0035] FIGS. 1 illustrates a puncture needle 1 with a contained needlestylet 2, which has a needle stylet tip 3. The puncture needle is of aknown design. What is essential is that the puncture needle 1 consistsof a paramagnetic material and thus may be applied in the MRT process.The puncture needle 1 has a length of approx. 200 mm and a diameter ofapprox. 1.3 mm. The needle stylet has a three-edged puncture tip whichextends beyond the puncture needle 1. A grip end enables the smoothremoval of the needle stylet 2 from the puncture needle 1.

[0036] FIGS. 2 illustrates a wire 4, which consists of stainless steel,with a special type of this wire 4 with a tongue end 5 being available,which is executed with a taper-ground tongue. In the depicted practicalexample the length of the wire is approx. 1 meter, with the tongue end 5being approx. 100 mm long. The wire 4 is made from a paramagneticmaterial.

[0037]FIGS. 3 and 4 illustrate the introducer tube 6 and the stylet 12.The introducer tube 6 and the stylet 12 are made from syntheticmaterials, such as PE, PTFE, FEP. The length of the introducer tube 6 isapprox. 100-200 mm and its diameter is approx. 1.5 mm up to 4mm—depending on the practical example. The stylet 12 that is containedin the introducer tube 6 is executed with close tolerances—depending onthe size of the introducer tube 6. The proximal end of the introducertube 6 is equipped with a silicone lamella 10 to which a T piece 9 isconnected. This silicone lamella 10 is designed as a silicone membranein the form of a forward-folding buckling lamella. The silicone lamella10 essentially improves handling of the introducer tube 6. The T piece 9is equipped with a hose lead 8 and an adjacent three-way faucet 7. Viathe three-way faucet 7 and the hose lead 8 to the T piece 9 it ispossible to apply additional local anesthetics, such as lubricant,tissue glue, alcohol, etc., which essentially contributes to providing alargely painless therapy also for capsular lesions. Furthermore the Tpiece 9 is equipped with an external thread 13 to lock the stylet 12with contained internal thread into the grip end 14. A membrane 16 isprovided between the T piece 9 and the adjacent external thread 13 whichprevents any fluids from leaking and facilitates a safe and non-slippingpositioning of the tunneled catheter 17. The introducer tube 6 isprovided with marks 11. These are preferably arranged at a distance of 1cm from each other along the entire length of the introducer tube 6.Thus an exact positioning of the introducer tube 6 is ensured. In itslocked state with the introducer tube 6 the stylet 12 has a length whichis distinguished in that approx. 1 cm of the stylet tip 15 extend fromthe distal end of the introducer tube 6.

[0038] A further preferred design is that the stylet 12 is executedhollow. This hollow design form of the stylet 12 provides an increasedlubricity during the insertion of the introducer tube 6 with the stylet12 via the wire 4 into the patient.

[0039]FIGS. 5 and 6 illustrate the tunneled catheters 17 according tothe invention with internal stylet 20. The tunneled catheter 17 madefrom a thermostable synthetic material which resists a max. temperatureof 400° C. The preferred materials employed are PTFE and FEP. Thetunneled catheter 17 has a length of approx. 400 mm. Essential of theinvention is here the existing tip at the distal end of the tunneledcatheter which is air- and fluid-tight sealed. The external diameter ofthe tunneled catheter may be between 1.5 mm and 4 mm, depending on theapplication form. This tunneled catheter 17 is equipped with an internalstylet 20 with a grip end 19. The internal stylet 20 is a wire which ismade from a paramagnetic material and provided with a plastics coating.It is through this internal stylet 20 that the tunneled catheter 17, dueto the high stability of the stainless steel wire, may be inserted withsafe positioning into the internal stylet 20, and there are furthercontrol opportunities for the positioning of the tunneled catheter 17.The upper part of the tunneled catheter 17 is provided opposite thetunneled catheter tip 21 with marks which are arranged at a distance of1 cm from each other. The first mark towards the tunneled catheter tip21 is arranged in such a manner that approx. 30 mm of the tunneledcatheter 17 project at the distal end of the introducer tube 6 uponinsertion into the introducer tube 6 and reaching of the first mark.After removing the internal stylet 20 by the grip end 19 an opticalwaveguide for laser treatment of the respective tumor may be smoothlyinserted. The positioning of the tunneled catheter 17 towards theintroducer tube 6 by means of the marks on the tunneled catheter 17according to the invention largely prevents that a fusion of the lightsource with the light impervious introducer tube 6 occurs duringtreatment with the optical waveguide since the tunneled catheter 17always projects approx. 30 mm from the distal end of the introducer tube6.

[0040]FIG. 7 illustrates a special embodiment of the tunneled catheterwith cooling which is made up as follows. The tunneled catheter 17 ofthe laser application set is employed in the same manner, with theproximal end of the tunneled catheter 17 being equipped with aconnection piece 22. A T piece 26 is connected to the connection piece22 via a connector 25. A pump to convey flushing and/or cooling agent isattached to the T piece 26. A sealing thread at the connection piece 22firmly interlocks a locking piece 23 of the inner tunneled catheter 30.The inner tunneled catheter 30 is located inside the tunneled catheter17. The inner tunneled catheter 30 is designed in such a manner that itends at the distal end 5 mm before the tunneled catheter tip 21. Theinner tunneled catheter 30 is open at the distal end. A connection of apump for a flushing and/or cooling agent is provided via a connector 24and a T piece 27 above the locking piece 23 of the inner tunneledcatheter 30. The cooling agent 31 flows via the T piece 24, connector25, locking piece 23 and through the inner tunneled catheter 30 into thetip of the of the inner tunneled catheter 30 and on its flow back theflushing and/or cooling agent 31 is led between the tunneled catheter 17and the inner tunneled catheter 30 via the connection piece 22,connector 25 and T piece 26 to the pump. Preferably a sterile isotonicsodium chloride solution is used as flushing and/or cooling agent. Thelaser applicator 33 is inserted into the inner tunneled catheter 30,thus ensuring maximum cooling of the entire punctured tissue, since thebackflow between the tunneled catheter 17 and the inner tunneledcatheter 30 transmits cooling to the entire area of the puncturedtissue—which consists an advantage that is essential of the invention.In order to seal off the of the laser applicator 33 or the removal ofthe internal stylet 20 of the laser application set, respectively, amembrane sealing 28 is arranged in the locking piece 23 of the innertunneled catheter 30. In order to seal off the insertion of the innertunneled catheter 30 a further membrane sealing 29 is provided in theconnection piece 22.

[0041]FIG. 8 illustrates the tip of the tunneled catheter 17 in itsembodiment. It can be seen that the cooling agent 31 exits in theinterior of the inner tunneled catheter 30 and at the outside of thetunneled catheter point 21 between the inner tunneled catheter 30 andthe tunneled catheter 17. The laser applicator 33 projects beyond thedistal end of the inner tunneled catheter 30, hence, the flushing and/orcooling agent cools the entire external tissue of the tumor to betreated.

[0042] The application according to the invention of the laserapplication set in a therapy of soft-tissue tumors is described asfollows:

[0043] The tumor to be treated is punctured with the puncture needle 1and the contained needle stylet 2 with its needle stylet tip 3. Thethree-edged needle stylet tip 3 makes for a good puncture efficiency ofthe puncture needle 1. Following the completion of a positive puncturethe needle stylet 2 is removed from the puncture needle 1. Subsequently,a wire 4 is inserted up to the distal end of the puncture needle 1. Thepuncture needle 1 is removed via this wire 4. Then the introducer tube 6with the locked stylet 12 is strung to the wire 4 and led into the tumorto be treated up to the distal end of the wire 4. The wire 4 is removedafter the exact positioning of the introducer tube 6 with the stylet 12.As required, the necessary additional local anesthetics are supplied tothe three-way faucet 7. A slight turn of the grip end 14 of the stylet12 undoes the locking with the T piece 9 of the introducer tube 6 andthe stylet 12 may be removed from the introducer tube 6.

[0044] A further preferred design is that marks are appended to theintroducer tube 6 which permit an exact positioning of the introducertube 6 into the tumor to be treated. Subsequently, the tunneled catheter17 with contained internal stylet 20 is inserted into the introducertube 6. While doing so, the marks on the tunneled catheter 17 permit anexact positioning of the introducer tube 6 into the tumor to be treated,with, as is essential of the invention, the first mark being designed insuch a way that the tunneled catheter 17 projects by 30 mm from thedistal end of the introducer tube 6. The internal stylet 20 is providedto improve correctability and stabilization during the insertion of thetunneled catheter 17. Following the removal of the internal stylet 20 bymeans of the grip end 19 an optical waveguide to perform the lasertherapy is inserted until the distal end of the tunneled catheter 17.The permanent monitoring by means of CT or MRT processes, respectively,permits a respective exact positioning of the tunneled catheter 17 withthe tunneled catheter point 21 according to the invention. Furthermore,the functioning of the inserted optical waveguide can be checked inorder to prevent a fusion of the light source with the light impervioussheath of the introducer tube 6. The exact positioning with the help ofthe introducer tube 6 and the tunneled catheter 17 also enables theremoval of defective optical waveguides and to replace such by a newoptical waveguide and thus avoid a new puncture. Following thecompletion of the treatment via optical waveguide the latter is removedand subsequently also the tunneled catheter 17 and the introducer tube6. While doing so it possible to introduce, e.g., tissue glue via thethree-way faucet 7 and the hose lead 8 to the T piece 9 during theremoval of the introducer tube 6 and thus an advantage according to theinvention is provided by ensuring a minimum cell dispersion of thetreated tumor while removing the introducer tube 6 which previously hasbeen an essential disadvantage of the laser therapy of tumors.

REFERENCE SIGNS

[0045]1. Puncture needle

[0046]2. Needle stylet

[0047]3. Needle stylet tip

[0048]4. Wire

[0049]5. Tongue-shaped end

[0050]6. Introductor tube

[0051]7. Three-way faucet

[0052]8. Hose lead

[0053]9. T piece

[0054]10. Silicone lamella

[0055]11. Mark

[0056]12. Stylet

[0057]13. External thread

[0058]14. Grip end

[0059]15. Stylet tip

[0060]16. Membrane

[0061]17. Tunneled catheter

[0062]18. Mark

[0063]19. Grip end

[0064]20. Internal stylet

[0065]21. Tunneled catheter tip

[0066]22. Connection piece

[0067]23. Locking piece

[0068]24. Connection

[0069]25. Connection

[0070]26. T piece

[0071]27. T piece

[0072]28. Membrane sealing

[0073]29. Membrane sealing

[0074]30. Inner tunneled catheter

[0075]31. Flushing and/or cooling fluid

[0076]32. Sealing thread

[0077]33. Laser applicator

1. A laser application set to treat tumors in which the distal end of atunneled catheter (17) from synthetic materials, preferably PE, FEP,PTFE, is air- and fluid-tight sealed and movably guides an opticalwaveguide (33), characterized in that an introducer tube (6) with aclosely fitting interior stylet (12) is provided and a tunneled catheter(17) is fitted with a closely fitting internal stylet (20), in which,upon removal of the stylet (12) from the introducer tube (6), thetunneled catheter (17) with the internal stylet (20) can be closelyfitting inserted into the introducer tube (6) and projects from thedistal end of the tunneled catheter (17) and in which the opticalwaveguide (33) can be inserted after the removal of the internal stylet(20) from the tunneled catheter (17).
 2. A laser application setaccording to claim 1 , characterized in that the introducer tube (6) andthe stylet (12) are open at their distal and proximal ends.
 3. A laserapplication set according to claim 1 , characterized in that the distalend of the tunneled catheter (17) is fitted with a tunneled catheter tip(21) and has an opening at its proximal end.
 4. A laser application setaccording to claim 1 , characterized in that the introducer tube (6) andthe tunneled catheter (17) are each provided with marks (18) and (11) sothat the tunneled catheter (17) projects 30 mm beyond the distal end ofthe introducer tube (6) upon introduction into the introducer tube (6).5. A laser application set according to claims 1 and 4, characterized inthat the marks (11,18) are arranged at a distance of 1 cm from eachother, with the introducer tube (6) being marked along its entirelength.
 6. A laser application set according to at least one of theaforementioned claims, characterized in that the proximal end of theintroducer tube (6) is equipped with a T piece (9), with a siliconelamella (10) being placed between the T piece (9) and the introducertube (6) and an external thread (13) fitted to the opposite side, withan interior membrane (16) and a hose lead (8) at the T piece (9) with athree-way faucet (7) fitted to its end.
 7. A laser application setaccording to at least one of the aforementioned claims, characterized inthat the stylet (12) is equipped with a grip end (14) with an internalthread which, in conjunction with the external thread (13) of theintroducer tube (6), enables the locking of the stylet (12).
 8. A laserapplication set according to at least one of the aforementioned claims,characterized in that the introducer tube (6) and the stylet (12) arehollow and from a material which is suitable for the MRT process,preferably PE, FEP, PTFE, etc.
 9. A laser application set according toat least one of the aforementioned claims, characterized in that thestylet (12) in locked state projects by approx. 10 mm from the distalend of the introducer tube (6) and has an open stylet tip (15).
 10. Alaser application set according to at least one of the aforementionedclaims, characterized in that the internal stylet (20) is made of awire, which preferably is from a paramagnetic material, and is enclosedby a synthetic sheathing.
 11. A laser application set according to claim1 , characterized in that a tunneled catheter (17) has an inner tunneledcatheter (30), and a firm connection between the two catheters (17 and30) can be made, and a space exists between the tunneled catheter (17)and the inner tunneled catheter (30), in which a laser applicator (33)is movably arranged.
 12. A laser application set according to claim 11 ,characterized in that, in order to establish a firm, separableconnection, a connection piece (22) is arranged at the tunneled catheter(17) and a locking piece (23) at the inner tunneled catheter (30), inwhich the connection piece (22) is provided with a sealing thread (32).13. A laser application set according to claims 11 and 12, characterizedin that locking piece (23) is provided with a membrane sealing (28)which is connected to a T piece (27) by means of a connector (24).
 14. Alaser application set according to claims 11 and 12, characterized inthat a locking piece (23) is provided with a membrane sealing (29) whichis connected to a T piece (26) by means of a connector (25).
 15. A laserapplication set according to claims 13 and 14, characterized in that apump to convey a flushing and/or cooling agent (31) is connected to theT piece (27 and 26).
 16. A laser application set according to claim 12 ,characterized in that the flushing and/or cooling agent (31), which isconveyed via the inner tunneled catheter (30) into the tunneled catheter(17) is preferably sterile isotonic sodium chloride solution.
 17. Alaser application set according to claim 12 , characterized in that theinner tunneled catheter (30) ends 5 mm before the tunneled catheter tip(21) at the distal end.
 18. A laser application set according to claim12 , characterized in that the inner tunneled catheter (30) is designedin such a manner that a backflow of the flushing and/or cooling agent isensured between the tunneled catheter (17) and the inner tunneledcatheter (30).